The former vice presidential candidate has been showing off that she's in good shape while sitting in the Dancing With the Stars audience cheering on daughter Briston. But on Sunday, a photo surfaced showing her looking "startlingly skinny," as Hollywood Life put it.

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"Our family is writing a book on fitness and self-discipline focusing on where we get our energy and balance as we still eat our beloved homemade comfort foods!" Palin, 48, told People.com in an email Tuesday.

She says she will discuss the topics in "our unique and motivating book." And Palin added, "We promise you what we do works and allows a fulfilling quality of life and sustenance anyone can enjoy."

People says it's unclear if Palin has a contract for the upcoming book or when the work will be published.